Research Institute for Biological Sciences, Okayama Prefecture, Kaga-gun, Okayama, 716-1241, Japan.
Plant Cell. 2011 Sep;23(9):3172-84. doi: 10.1105/tpc.111.088641. Epub 2011 Sep 2.
TERMINAL FLOWER1 (TFL1) is a key regulator of flowering time and the development of the inflorescence meristem in Arabidopsis thaliana. TFL1 and FLOWERING LOCUS T (FT) have highly conserved amino acid sequences but opposite functions. For example, FT promotes flowering and TFL1 represses it; FT-overexpressing plants and TFL1 loss-of-function mutants have a similar phenotype production of terminal flowers in the shoot apex. FT is believed to function in a transcriptional activator complex by interacting with FD. Here, we demonstrate that TFL1 is involved in the transcriptional repression of genes that are activated by FT. We analyzed transgenic plants overexpressing TFL1 fused to a transcriptional repressor domain (TFL1-SRDX) or an activator domain (TFL1-VP16). Plants carrying 35S:TFL1-SRDX showed delayed flowering similar to 35S:TFL1 plants, and plants carrying 35S:TFL1-VP16 showed an early flowering phenotype and produced terminal flowers. Furthermore, the tfl1 and 35S:TFL1-VP16 plant phenotypes were strongly suppressed by the fd mutation, and TFL1 interacted with FD in the cell nucleus, as shown by bimolecular fluorescence complementation experiments. We conclude that TFL1 negatively modulates the FD-dependent transcription of target genes to fine-tune flowering time and the development of the inflorescence meristem.
终端花 1（TFL1）是拟南芥开花时间和花序分生组织发育的关键调节因子。TFL1 和开花时间基因（FT）具有高度保守的氨基酸序列，但功能相反。例如，FT 促进开花，而 TFL1 抑制开花；FT 过表达植物和 TFL1 功能丧失突变体具有相似的表型——在茎尖产生顶端花。FT 被认为通过与 FD 相互作用在转录激活复合物中发挥作用。在这里，我们证明 TFL1 参与了由 FT 激活的基因的转录抑制。我们分析了过表达与转录抑制结构域（TFL1-SRDX）或激活结构域（TFL1-VP16）融合的 TFL1 的转基因植物。携带 35S:TFL1-SRDX 的植物表现出与 35S:TFL1 植物相似的开花延迟，而携带 35S:TFL1-VP16 的植物表现出早花表型并产生顶端花。此外，tfl1 和 35S:TFL1-VP16 植物表型被 fd 突变强烈抑制，并且 TFL1 在细胞核中与 FD 相互作用，如双分子荧光互补实验所示。我们得出结论，TFL1 负调控 FD 依赖性靶基因的转录，以微调开花时间和花序分生组织的发育。
